The traditional surgical procedure for anastomosing the ends of a severed vessel has been a suturing operation. The ends of the vessel are stitched together while the fluid flow in the vessel is clamped off. Due to the relatively small size of the vessel and the relative difficulty in stitching around the circumference of the vessel, the traditional suturing technique is somewhat time-consuming. The vessel itself and the tissue supplied with fluid by the vessel can become damaged, due to the terminated flow of fluid while the vessel is clamped off, if the procedure becomes too time-consuming. Also, fluid sometimes leaks from the vessel where the sutures penetrate the vessel walls.
Various surgical prostheses and techniques have been devised to improve the ability to achieve successful anastomosis and to reduce the time consumed by the anastomosis procedure. Tubular prostheses have been inserted into the interior and over the exterior of the vessel which is anastomosed. Such prostheses aid in holding the vessel ends during the procedure and while the vessel tissue grows back together during healing. Some of the prostheses are made from biological material which is slowly absorbed by the body tissue as the healing progresses. The biological material is usually a chemical or solid material which dissolves slowly over a period of weeks by chemical or biological absorption. Other types of prostheses are made from permanent materials, such as plastics or metals, which remain permanently within the interior of the vessel after healing is completed. Other prostheses incorporate both permanent and biologically absorbable materials. As the biologically absorbable materials dissolve, they are replaced by natural tissue growth and the permanent materials are thus permanently incorporated into the living tissue.
The prostheses which are biologically dissolvable or absorbable are sometimes regarded as preferable, because no foreign object remains after the healing is completed. However, they also present disadvantages. Permanent prostheses can partially occlude a vessel and thereby permanently reduce the fluid flow therethrough. The living tissue may attempt to reject the foreign body of the prostheses. Unnatural tissue growth caused by adverse tissue reaction may fully or partially occlude the vessel. An additional surgical procedure is often required to remove the remaining permanent prostheses after anastomosis is complete, or if medical complications result from tissue rejection.
A relatively new procedure for anastomosis involves completely bonding the ends of the vessel together, usually by a laser beam. Thermal bonding heats the ends of the vessel and creates an interlinked and cross-linked matrix of dessicated tissue fibers which hold the ends of the vessel together until natural tissue growth occurs. One advantage of thermal bonding is that a continuous bonded "seam" is created to obtain a more complete and leak-free junction of the vessel ends than is possible by using a number of spaced stitches in the traditional suturing operation. Thus, better anastomosis is possibly achieved by use of the thermal bonding technique.
One disadvantage of anastomosis by thermal bonding is that it requires about the same amount of time to complete as the more traditional anastomosis by use of the surgical suturing technique. Prior to thermal bonding by application of a laser beam or other thermal energy bonding beam, the vessel ends must be aligned, abutted and held together without the aid of metallic clamps or the like. Metallic clamps or the like would divert or deflect the energy beam and might cause undesirable localized heating and tissue destruction. To align and hold the vessel ends prior to application of the thermal bonding beam, three stay sutures or stitches are typically taken at 120.degree. intervals around the circumference of the vessel. Inserting the three stay sutures consumes almost as much time as the traditional technique of completely suturing around the circumference of the vessel. The three stay sutures can also bend or otherwise influence the energy beam to create a somewhat uneven distribution or application of the energy beam to the vessel. The degree or density of tissue bonding may therefore be influenced from location to location around the circumference of the vessel. The stay sutures also pose some risk of being rejected by the tissue and, of course, the insertion of the sutures themselves requires the ends of the already damaged vessel to be pierced during stitching, which further damages the vessel and creates a possibility for fluid leakage.